This invention relates to the treatment of amblyopia, also known as xe2x80x9clazy eyexe2x80x9d, in children. Particularly, the invention utilizes a pair of glasses fitted with LCD lenses that are selectively made opaque in order to force the child to exercise the weak eye.
Amblyopia (lazy eye) is probably the most common cause of monocular blindness. It occurs in about 4% of the population, with between 80,000-160,000 new cases occurring yearly in the United States. This neurological condition is believed to occur due to a neural input imbalance of either the optical power of the eyes or ocular misalignment. Both of these conditions may result in an incompatible binocular visual input to the visual centers of the brain that prevents a normal, single visual perception. This incompatability of visual perception induces a competitive inhibition between the two eyes resulting in a xe2x80x9cstrong eyexe2x80x9d and a xe2x80x9cweak eyexe2x80x9d. Here, the visual utility of the xe2x80x9cstrong eyexe2x80x9d becomes dominant over the xe2x80x9cweak eyexe2x80x9d and results in permanent structural degradation of the cellular anatomy of portions of the lateral genticulate body and visual cortex of the occipital lobe of the brain. This degradation results in loss of visual acuity and loss of higher order binocular functions, such as stereopsis. After visual maturity of the child is reached, which is about 10 years of age, the disease becomes permanent.
The accepted treatment of this disorder involves blocking or reducing vision in the strong, good eye, as by a patch, in order to force the weaker eye to xe2x80x9cwork harderxe2x80x9d. This establishes and reinforces the development of neural pathways in the brain to cause proper connections to develop between the weak, amblyopic eye and the visual cortex. After a period of time, which may be between months and years, use of the patch is gradually reduced, affording both eyes the opportunity to develop normal binocular vision.
There exist two primarily accepted methods for treating amblyopia. The most effective method involves placing a patch over the strong eye, forcing the weak eye to work harder and reinforce neural pathways for vision in the brain. One commonly recommended regimen is to patch the strong eye for up to a week for every year of the child""s age until vision is restored, with the process being repeated if there is no improvement.
Problems with patching are basically that the patient cannot see well and the obviousness of the patch creates negative social implications. This in turn typically generates resistance and poor compliance from the child, and anxiety in both the child and parents. Medically, the practice of patching is not without risk. One such risk is that of inducing a crossing of the child""s eyes in those types of amblyopia in which the eyes are undeviated with a hyperopic refractive error. Reversing of the amblyopic condition to the strong eye has also been reported. In addition, development of normal binocular vision during the patching treatment is interrupted.
A device has been developed that monitors and records actual wearing time of the patch so that in cases where there is no medical improvement of the patient, a physician can determine whether the failure was due to noncompliance or possibly due to a different underlying disorder. During the use of this device, it was discovered that the practice of patching had a very poor compliance rate. Here, it was found that actual average compliance rate was on the order of only about 5 minutes a day, yet many of these children had successful results. With this finding, it is believed that strict compliance of only 30 minutes or so a day may result in successful treatment.
In an attempt to overcome the difficulties of patching, a technique known as xe2x80x9cpenalizationxe2x80x9d has been developed. In this treatment, the strong eye is optically and pharmacologically weakened so that the child is forced to use the weak eye more. However, this treatment is less effective and is used more for maintenance than treatment.
In addition to the foregoing, it has been suggested that if the child is immersed in an activity during periods of treatment, such a play activity or other activity that requires concentration by the child, recovery occurs more rapidly than if the child is not focussed or not concentrating. As such, an interactive computer game or interesting video that holds the interest of the child may accelerate treatment time.
Apparatus for treating diseases of the class including amblyopia is disclosed. An eyeglasses frame or goggles is adapted to hold LCD cells that the patient looks through, with circuitry coupled to each of the LCD cells. The circuitry may be configured to provide control signals to the LCD cells so that the strong eye is either partially or fully occluded.